JPH11138659A - Manufacture of silicone rubber blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicone rubber blade having an excellent edge accuracy to obtain a great variety of product by a low-cost investment in facility. SOLUTION: In the method for manufacturing a silicone rubber blade comprising the steps of casting a mixture of a liquid-like silicone rubber and a curing agent in a mold having an upper mold 1 including a flat mold surface and a lower mold 2 having a blade molding recess 23 and flash receiving grooves 22a, 22b disposed on a periphery of the recess 23 and engraved on a parting surface by opening, and molding it by curing; the mixture of an amount exceeding a dosage of the recess 23 is cast in the recess 13, and the mold 1 is mated to the mold 2 and clamped while the cast mixture is exhibiting a stringing gel state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silicone rubber blade having an excellent edge precision and which can be manufactured with low capital investment.

[0002]

2. Description of the Related Art In an electrophotographic apparatus, an elastic blade is a developing blade for carrying a thin layer of toner on the outer periphery of a developing roller and charging the toner by friction.
It is used as a cleaning blade for cleaning residual toner on a photoreceptor, a fixing blade for scraping off powder, talc and the like on a fixing roller and cleaning the fixing roller.

As such elastic blades, silicone rubber blades are widely used because they are non-adhesive, have excellent triboelectric charging properties, and are excellent in heat resistance. As the silicone rubber forming the silicone rubber blade, those obtained by peroxide crosslinking, condensation reaction crosslinking, addition reaction crosslinking, etc. are mainly used, but as an elastic blade used as various blades of an electrophotographic apparatus, When an by-product is generated during the reaction, the by-product is deposited on the blade surface and adversely affects the image quality. Therefore, an addition-reaction type in which no by-product is generated by the reaction is preferably used.

[0004] Among the silicone rubbers of the addition reaction type, liquid silicone rubber is particularly preferred due to its mechanical properties, but the viscosity of the raw material of liquid silicone rubber is generally 100,000 c.
Since it has a high viscosity of about ps, there is a drawback that if air is bitten into the raw material and the mixed solution, it cannot be easily defoamed. For this reason, in the production of silicone rubber blades using liquid silicone rubber, liquid silicone rubber is precisely measured by a cylinder of an injection molding machine using a molding device combining a two-liquid mixing device and an injection molding machine. rear,
A method of injecting into a closed mold finished with high accuracy in a completely sealed state has been common.

In such a conventional method of manufacturing a general silicone rubber blade, the injection molding machine used is required to have a performance capable of accurately measuring the liquid silicone rubber without biting the air. ,Also,
In order to prevent the liquid silicone rubber from being cured in the injection molding machine, it is necessary to heat the mold while cooling the cylinder of the injection molding machine and the nozzle portion that contacts the mold. However, even in this case, troubles such as hardening of the liquid silicone rubber at the nozzle tip are often observed, and in order to prevent such problems from occurring, it is necessary to control the temperature of the molding apparatus and the mold. In addition, a higher level of technology is required for an air removal mechanism, higher precision, and the like, and the molding equipment as well as the mold are considerably expensive, and the initial equipment investment is enormous.

In addition, since the device itself becomes large-scale,
When the size of the silicone rubber blade or the composition of the liquid silicone rubber changes, the step cannot be easily changed, and there is a problem that it is not suitable for multi-product production. However, the electrophotographic apparatus has various market needs such as high image quality, colorization, low cost, and personalization. As a result, elastic blades are required to have various types and sizes. As a result, elastic blades using liquid silicone rubber could be supplied only to a large number of product models on the market.

[0007]

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method of manufacturing a silicone rubber blade having excellent edge accuracy, which enables a wide variety of products to be obtained with low capital investment. Is what you do.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a mixture of a liquid silicone rubber and a curing agent is coated with an upper mold 1 having a flat mold surface, a blade forming recess 23 and a burr receiver arranged around the recess. A method for producing a silicone rubber blade, which is formed by injecting into a mold composed of a lower mold 2 in which a groove 22 and a mold opening surface are opened and engraved, and molding by curing. An amount exceeding the dose of the blade forming recess is injected into the blade forming recess 23, and the upper mold 1 is matched with the lower mold 2 while the mixture after injection is in a stringy gel state. This is a method of manufacturing a silicone rubber blade to be clamped. Hereinafter, the present invention will be described in detail.

In the method for producing a silicone rubber blade of the present invention, a mixture of a liquid silicone rubber and a curing agent is injected into a mold and cured to be molded.

As shown in FIG. 1, the mold has an upper mold 1 having a flat mold surface, and a blade forming recess 23 and a burr receiving groove 22 disposed around the recess 23 are open to the mold mating surface. The lower die 2 is formed by engraving. The mold shown in FIG. 1 is an example of the mold used in the present invention, and includes an upper mold having a flat mold surface, a blade forming recess and a burr receiving groove arranged around the recess. The mold is not limited to the mold shown in FIG. 1 as long as it is a mold composed of a lower mold opened and engraved on the mold mating surface.

In the present invention, the mixture is injected into the blade-forming recess 23 in an amount exceeding the capacity of the blade-forming recess, and while the mixture after injection exhibits a stringing gel state, The upper die 1 is matched with the lower die 2 and clamped. That is, an excessive amount of the mixture is injected into the blade forming concave portion 23, and the mixture is clamped at a timing when the mixture is in a stringing gel state due to the heat from the lower mold 2, whereby the excess amount of the mixture is reduced. Is pushed out of the blade forming recess 23 together with the air. The mixture containing the extruded air is injected into the burr receiving groove 22a and the burr receiving groove 22b to form a burr. For this reason, the obtained silicone rubber blade has burrs, but all the air is present in the burrs. By removing the burrs, the finally obtained silicone rubber blade becomes the air. Which is excellent in edge accuracy without the presence of.

Therefore, in the present invention, it is necessary to inject the mixture into the blade forming recess 23 in an amount exceeding the capacity of the blade forming recess. If the mixture is not injected in an amount exceeding the capacity of the blade-forming concave portion, no material for forming burrs will be present, and air will remain in the finally obtained silicone rubber blade.

Further, in the present invention, the above mold clamping is
It is necessary to carry out while the above mixture is in a stringy gel state. If the mold is clamped before the mixture exhibits the stringing gel state, the air does not completely escape into the burr, and the air remains in the finally obtained silicone rubber blade. Further, if the timing of the mold clamping is too late, the liquid mixture does not sufficiently extend into the blade forming recesses 23, and the finally obtained silicone rubber blade has poor filling or poor thickness. Or a parting line occurs. In addition,
The stringing gel state is a state in which the liquid mixture starts to harden and the viscosity increases, and when the needle or the like is brought into contact with the mixture and the needle or the like is released again, the mixture extends in a stringing shape. State.

The mold temperature is preferably 110 to 180 ° C. If the temperature is lower than 110 ° C., the time required for demolding becomes extremely slow, thereby hindering the productivity. If the temperature exceeds 180 ° C., the gelation of the mixture is too fast, and an air or parting line remains on the injection surface. there is a possibility. Also,
When the mixture is injected, the mold temperature is set lower than the temperature range. After the mixture is injected, the mold temperature is increased to 110 to 180 ° C., and after the mixture is gelled, the mold clamping is performed. May be implemented.

The above clamping pressure is preferably 10 kg / cm ² or more. If it is less than 10 kg / cm ² , the gel-like mixture cannot be mold-clamped accurately, and air will remain in the finally obtained silicone rubber blade, or the thickness of the obtained silicone rubber blade will be reduced. Failure occurs. If it is 10 kg / cm ² or more, a molded article having no thickness and excellent in thickness accuracy can be obtained. However, even if the viscosity of the cured product at the time of gel is taken into consideration, it is meaningless to significantly increase the pressure. Usually, up to 40 kg / cm ² is sufficient.

The mixture of the liquid silicone rubber and the curing agent used in the present invention is not particularly limited, and examples thereof include commercially available products such as "TLM1404" manufactured by Toshiba Silicone Co., Ltd. The method of measuring and mixing the liquid silicone rubber and the curing agent for preparing the mixture is not particularly limited, and can be performed by a conventionally known method or the like. There may be.

The silicone rubber blade obtained by the method for producing a silicone rubber blade of the present invention is suitably used as an elastic blade of an electrophotographic apparatus such as a developing blade, a cleaning blade, and a fixing blade.

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 TLM1404 (manufactured by Toshiba Silicone Co., Ltd.) was used as a liquid silicone rubber material. Weigh 10 g each of the main agent and hardener into a container, and use a spatula to remove 15 g by hand.
Stir well for minutes and mix. The mixed liquid had a considerable bite of air due to stirring, but was not subjected to any defoaming treatment or the like. The lower mold 2 shown in FIG. 1 was preheated to 180 ° C., and 12 g of the mixed liquid was poured therein. Approximately 15 seconds later, the state of the stringing gel was reached.
After pressing for 1 minute at a pressure of g / cm ^2, the press was released and the molded product with burrs was taken out. The molded article was transparent without any air. The net weight of the molded article was 9.5 g. The burr portion contained a large amount of air. The molded product was cut into a predetermined size to obtain an elastic blade. The results are shown in Table 1.

[0020] the Example 2 the mold temperature to 110 ° C., and the upper mold so reached after approximately 2 minutes to the state of stringing gel, 15 at a pressure of 10 kg / cm ²
An elastic blade was obtained in the same manner as in Example 1, except that heating was performed for one minute. The results are shown in Table 1.

[0021] Example 3 The mold temperature was brought to 0.99 ° C., and the upper mold so reached after about 30 seconds of the state of stringing gel, 3 at a pressure of 20 kg / cm ²
An elastic blade was obtained in the same manner as in Example 1, except that heating was performed for one minute. The results are shown in Table 1.

Comparative Example 1 An elastic blade was obtained in the same manner as in Example 1 except that the amount of the liquid to be charged was 9.5 g, which was the same as the net amount of the molded article. Air was mixed at the end of the molded product. This is presumably because the air could not escape from the end portion because there was no material to become burrs. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 An elastic blade was obtained in the same manner as in Example 1 except that after the liquid was injected, the pressing was performed before the stringing gel was obtained. Fine air was mixed in the center of the molded product. this is,
It is considered that the viscosity was low at the time of pressing because the pressing was performed before gelation, the air could not be sufficiently expelled, and the air was hardened in a state where the air remained in the molded article. The results are shown in Table 1.

[0024]

[Table 1]

[0025]

The method for producing a silicone rubber blade according to the present invention has the above-described structure, so that even when a large amount of air is mixed in the mixture of the liquid silicone rubber and the curing agent, the air is mixed. It is possible to obtain a silicone rubber blade with no edge and excellent edge accuracy. In addition, since air may be chewed in operations such as weighing and mixing when preparing the mixture, a known inexpensive method can be used in preparing the mixture. For example,
Since a silicone rubber blade having excellent quality can be obtained by hand operation, it is possible to easily cope with the manufacture of a handmade sample.

Further, since it is assumed that a small amount of burrs are formed in advance, the precision of the mold used is not as required as in the conventional injection molding method. Further, since it is not necessary to bring the injection nozzle into contact with the mold for injection into the open mold, there is no occurrence of trouble such as curing of the mixture at the nozzle tip.

Therefore, the method for producing a silicone rubber blade according to the present invention can be carried out with inexpensive equipment, and can cope with multi-product production.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a mold used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper die 2 Lower die 22a Burr receiving groove 22b Burr receiving groove 23 Blade forming recess 3 Set of knock pin and spring for receiving upper die

Claims (3)

[Claims] An upper mold having a flat mold surface, a blade forming recess and a burr receiving groove arranged around the mixture are formed on a mold mating surface. A method for producing a silicone rubber blade, which is formed by injecting into a mold formed of a lower mold 2 that is opened and engraved, and curing and curing the mixture, wherein the mixture is placed in the blade forming recess 23. Injecting more than the dose of the blade forming concave portion, and the upper mold 1 is matched with the lower mold 2 and the mold is clamped while the mixture after injection exhibits a stringing gel state. A method for manufacturing a silicone rubber blade. 2. The mold temperature is 110 to 180 ° C.,
Clamping pressure, 10 kg / cm ² or more in the production method of the silicone rubber blade according to claim 1, wherein. 3. The method according to claim 1, wherein the silicone rubber blade is a developing blade, a cleaning blade, or a fixing blade.